Nec Corporation

Nec Energy Devices, Ltd.

Tatsuji Numata

Daisuke Kawasaki

Jiro Iriyama

Tetsuya Kajita

Ryuichi Kasahara

Hiroo Takahashi

Takehiro Noguchi

Akira Kobayashi

Shin Serizawa

Masato Shirakata

Masatomo Yonezawa

Chika Kanbe

Mikio Watanabe

Kazuhiko Inoue

Koji Utsugi

Hiroshi Yageta

Yasutaka Kono

Yuki Kusachi

Emiko Fujii

Tomokazu Kumeuchi

Chika Kambe

Yutaka Bannai

Yoshitada Tomioka

The object of an exemplary embodiment of the invention is to provide a lithium ion secondary battery having an excellent charge and discharge cycle property. An exemplary embodiment of the invention is a lithium ion secondary battery, comprising a battery assembly in which a positive electrode and a negative electrode are stacked through a separator and a package in which the battery assembly and an electrolyte are placed; wherein the negative electrode comprises a negative electrode collector which is composed of a metal and a negative electrode active material layer which is formed on the negative electrode collector and which comprises a negative electrode active material and a binder; wherein the negative electrode collector and the negative electrode active material layer have a crack which is formed so as to be communicated with each of them; and wherein the crack reaches an outer peripheral edge from an inside of the negative electrode.

Lithium ion secondary battery

A control system for a lithium secondary battery measures a voltage V of a negative electrode that uses silicon oxide as a negative electrode active material, with respect to a lithium reference electrode and a discharge capacity Q of the lithium secondary battery during discharge of the lithium secondary battery; generates a V&#x2212;dQ/dV curve representing a relationship between dQ/dV, which is a proportion of an amount of change dQ in the discharge capacity Q to an amount of change dV in the voltage V, and the voltage V; calculates an intensity ratio of two peaks appearing on the V&#x2212;dQ/dV curve for two voltage values in the voltage V; and senses a state of the negative electrode utilizing the intensity ratio.

System and method for detecting a state of a lithium secondary battery by measuring a voltage of a negative electrode with respect to a reference electrode

Provided is a negative electrode active material for a lithium secondary cell, the material having the function of a binder for the active material, and being capable of stable reversible reactions with lithium. Also, provided are an extended-life lithium secondary cell having improved energy density and stable charge/discharge, and a method for producing the same. The negative electrode active material for a lithium secondary cell is polyimide represented by formula (1) (wherein R1 and R2 independently denote an alkyl, alkoxy, acyl, phenyl, or phenoxy group).

Negative electrode active material for lithium secondary cell, lithium secondary cell employing the same, and method for producing the same

Provided is a nonaqueous electrolytic solution secondary battery having a high energy density, and a positive electrode and a negative electrode used therefor. The nonaqueous electrolytic solution secondary battery includes a positive electrode and a negative electrode, wherein: the negative electrode contains a negative electrode active material having an initial charge/discharge efficiency of 75% or less when charged and discharged by employing metallic Li as a counter electrode; and the positive electrode contains a metal oxide (X) represented by AMeO(wherein A is Na and/or K, Me is Ni and/or Cu, x satisfies 1.9&#x2266;x&#x2266;2.1, and y satisfies 1.9&#x2266;y&#x2266;2.1).

Nonaqueous electrolytic solution secondary battery, and positive electrode and negative electrode used in the same

There is provided a negative electrode for a nonaqueous electrolyte secondary battery in which when a battery is formed, the energy density is high, and moreover, the decrease in charge and discharge capacity is small even if charge and discharge are repeated. By using silicon oxide particles having a particle diameter in a particular range as a starting raw material, and heating these particles in the range of 850&#xb0; C. to 1050&#xb0; C., Si microcrystals are deposited on the surfaces of the particles. Then, by performing doping of Li, a structure comprising a plurality of protrusions having height and cross-sectional area in a particular range is formed on the surfaces. The average value of the height of the above protrusions is 2% to 19% of the average particle diameter of the above lithium-containing silicon oxide particles. By using the lithium-containing silicon oxide particles obtained by the above means as a negative electrode active material, a negative electrode for a nonaqueous electrolyte secondary battery is fabricated.

Negative electrode for nanaqueous electrolyte secondary battery, nonaqueous electrolyte secondary battery using the same, and method for manufacturing negative electrode for nonaqueous electrolyte secondary battery

The object of an exemplary embodiment of the invention is to provide a negative electrode having excellent cycle property. An exemplary embodiment of the invention a method for doping and dedoping lithium for the first time after a negative electrode for a lithium secondary battery comprising silicon oxide as an active material is produced, comprising doping the lithium within the following current value range (A) and within the following doped amount range (B); current value range (A): a range of a current value in which a doped amount in which only one peak appears at 1 V or less on the V-dQ/dV curve becomes maximum, wherein the V-dQ/dV curve represents a relationship between voltage V of the negative electrode with respect to a lithium reference electrode and dQ/dV that is a ratio of variation dQ of lithium dedoped amount Q in the negative electrode to variation dV of the voltage V, and doped amount range (B): a range of a doped amount in which only one peak appears at 1 V or less on the V-dQ/dV curve.

Method for doping and dedoping lithium into and from negative electrode and method for producing negative electrode for lithium secondary battery

A secondary battery according to the present exemplary embodiment is a secondary battery including a laminated electrode body provided with at least one pair of positive and negative electrodes and an outer enclosure that accommodates the laminated electrode body, wherein the outer enclosure includes one or more concave portions, inside a border corresponding to an outer edge of an electrode surface of an outermost layer of the laminated electrode body, on a surface facing the electrode surface, and wherein, when a band-shaped outer circumferential region having an area that is a half of an area inside the border is set inside the border, at least one of the concave portions is located inside the outer circumferential region.

Secondary battery

There is provided a control system for a lithium secondary battery that can quantitatively sense a deterioration state inherent in a lithium secondary battery using silicon oxide as a negative electrode active material, that is, the nonuniform reaction state of a negative electrode. A control system for a lithium secondary battery including a positive electrode, a negative electrode using silicon oxide as a negative electrode active material, and a lithium reference electrode having a reference potential with respect to the negative electrode includes measurement means for measuring a voltage V of the negative electrode with respect to the lithium reference electrode and a discharge capacity Q of the lithium secondary battery during discharge of the lithium secondary battery; generation means for generating a V-dQ/dV curve representing a relationship between dQ/dV, which is a proportion of an amount of change dQ in the discharge capacity Q to an amount of change dV in the voltage V, and the voltage V; calculation means for calculating an intensity ratio of two peaks appearing on the V-dQ/dV curve for two voltage values in the voltage V; and sensing means for sensing a state of the negative electrode utilizing the intensity ratio.

Lithium secondary battery and control system therefor, and method for detecting state of lithium secondary battery

In a lithium ion secondary battery including a positive electrode, a separator, a negative electrode, and a package body, the negative electrode includes simple substance silicon as a negative electrode active material, and a negative electrode binder, and is doped with lithium, and the following formulas (1) and (2) are satisfied:1.2&#x2266;&#x2266;1.9&#x2003;&#x2003;(1)1.0&#x3c;/()&#x3c;1.6&#x2003;&#x2003;(2)wherein an amount of lithium inserted into the negative electrode until the negative electrode reaches a potential of 0.02 V with respect to metal lithium is M(a number of atoms), an amount of lithium released from the positive electrode until the positive electrode reaches a potential of 4.3 V with respect to metal lithium is M(a number of atoms), and an amount of lithium with which the negative electrode is doped is M(a number of atoms).

Lithium ion secondary battery and method for manufacturing the same

The invention provides a lithium ion secondary battery comprising a positive electrode, a negative electrode and an electrolysis solution containing an aprotic solvent having an electrolyte dissolved in it, wherein the negative electrodes uses an amorphous carbon material as a negative electrode active material. The amorphous carbon material has (A) an average particle diameter (median size) of 7 &#x3bc;m to 20 &#x3bc;m inclusive as measured by a laser diffraction scattering method and (B) a particle size distribution as measured by a laser diffraction scattering method, in which distribution the ratio of particles of less than 3 &#x3bc;m in diameter is 1% by mass to 10% mass inclusive, and is free of an electrical conducting material.

A lithium secondary battery which has excellent characteristics such as energy density and electromotive force and is excellent in cycle life and storage stability is provided. The secondary battery comprises a positive electrode, a negative electrode, and an electrolyte solution comprising an aprotic solvent having at least an electrolyte dissolved therein, wherein the positive electrode comprises a lithium-manganese composite oxide having a spinel structure as a positive electrode active material, and the electrolyte solution comprises a compound represented by the general formula (1).

A life of a secondary battery is extended, increase in a resistance when storing a secondary battery at an elevated temperature is prevented, and increase in a resistance during a charge-discharge cycle is prevented. A positive electrode active material comprising a lithium manganate and a lithium nickelate are used. The lithium manganate is a compound represented by the following formula (1) or the compound in which some of Mn or O sites are replaced with another element:LiMnO&#x2003;&#x2003;(1)

Positive electrode active material for secondary battery, positive electrode for secondary battery, secondary battery and method for producing positive electrode active material for secondary battery

A positive electrode active material containing lithium manganate having a spinel structure is used, wherein the value of a* of the L*a*b* color specification system is made to satisfy the requirement: &#x2212;3.2 &#x2266;a*&#x2266;&#x2212;1.4. Or, the value of a* is made to satisfy the requirement: &#x2212;5.8 23 a*&#x2266;&#x2212;4.2. Or, the value of L* is made to satisfy the requirement: 24 &#x2266;L*&#x2266;27.

Positive electrode active material for a secondary battery, secondary battery and process of manufacturing positive electrode active material for a secondary battery

A cathode active material for a secondary battery including a lithium-manganese composite oxide having a spinel structure and represented by the following general formula (I), Li(MMnYA)(OZ) (I), wherein 0.5&#x2266;x&#x2266;1.2, 0&#x2266;y, 0&#x2266;z, x+y+z&#x3c;2, 0&#x2266;a&#x2266;1.2 and 0&#x2266;w&#x2266;1; M contains at least Co and may further contains at least one element selected from the group consisting of Ni, Fe, Cr and Cu; Y is at least one element selected lo from the group consisting of Li, Be, B, Na, Mg, Al, K and Ca; A is at least one of Ti and Si; and Z is at least one of F and Cl. When the cathode active material for the secondary battery is used as the cathode for the a secondary battery, a higher operating can be realized while suppressing the reliability reduction such as the capacity decrease after the cycles and the deterioration of the crystalline structure at a higher temperature.

Positive electrode active material for secondary cell, positive electrode for secondary cell using same, and secondary cell

A positive electrode active material for a secondary battery contains a spinel lithium manganese composite oxide expressed by a general formula of Li(MMnA)Owhere x and y are positive values which satisfy 0.4&#x3c;x, 0&#x3c;y, x+y&#x3c;2, and 0&#x3c;a&#x3c;1.2. 'M' denotes Ni and at least one metal element selected from the group consisting of Co, Fe, Cr and Cu. 'A' denotes at least one metal element selected from the group consisting of Si and Ti. The ratio y of A has a value of 0.1&#x3c;y in case where A includes only Ti. Accordingly, it is possible to acquire a material for the positive electrode of a lithium ion secondary battery, which has a high capacity and a high energy density with a high voltage of 4.5 V or higher with respect to Li.

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Tokyo, Japan

Tatsuji Numata